Multi-speed transmission

Abstract

A transmission gearing arrangement produces at least nine forward speed ratios and one reverse speed ratio by selective engagement of three shift elements in various combinations. One embodiment includes four simple planetary gear sets, four clutches, and two brakes. Another embodiment includes two axis transfer gear pairs, three simple planetary gear sets, four clutches, and two brakes.

What is claimed is: 
     
       1. A transmission comprising:
 an input; 
 an output; 
 first, second, third, fourth, and fifth shafts; 
 a first gearing arrangement configured to impose a fixed linear speed relationship among the first shaft, the second shaft, and the third shaft; 
 a second gearing arrangement configured to impose a fixed linear speed relationship among the fourth shaft, the third shaft, and the second shaft; 
 a third gearing arrangement configured to impose a fixed linear speed relationship among the third shaft, the input, and the fifth shaft; 
 a fourth gearing arrangement configured to selectively constrain the output to rotate at a first speed ratio relative to the third shaft; 
 a fifth gearing arrangement configured to selectively constrain the output to rotate at a second speed ratio relative to the fifth shaft, the second speed ratio having an absolute value greater than an absolute value of the first speed ratio; 
 a first clutch configured to selectively couple the fourth shaft to the input; 
 a second clutch configured to selectively couple the first shaft to the input; 
 a first brake configured to selectively hold the first shaft against rotation; and 
 a second brake configured to selectively hold the second shaft against rotation. 
 
     
     
       2. The transmission of  claim 1  further comprising a one-way-brake configured to constrain the second shaft to rotate in only one direction. 
     
     
       3. The transmission of  claim 1  wherein the first gearing arrangement comprises a first simple planetary gear set having a first sun gear fixedly coupled to the first shaft, a first ring gear fixedly coupled to the third shaft, a first planet carrier fixedly coupled to the second shaft, and at least one planet gear supported for rotation on the first planet carrier and in continuous meshing engagement with the first sun gear and the first ring gear. 
     
     
       4. The transmission of  claim 1  wherein the second gearing arrangement comprises a second simple planetary gear set having a second sun gear fixedly coupled to the fourth shaft, a second ring gear fixedly coupled to the second shaft, a second planet carrier fixedly coupled to the third shaft, and at least one planet gear supported for rotation on the second planet carrier and in continuous meshing engagement with the second sun gear and the second ring gear. 
     
     
       5. The transmission of  claim 1  wherein the third gearing arrangement comprises a third simple planetary gear set having a third sun gear fixedly coupled to the third shaft, a third ring gear fixedly coupled to the fifth shaft, a third planet carrier fixedly coupled to the input, and at least one planet gear supported for rotation on the third planet carrier and in continuous meshing engagement with the third sun gear and the third ring gear. 
     
     
       6. The transmission of  claim 1  wherein the fourth gearing arrangement comprises:
 a fourth simple planetary gear set having a fourth sun gear fixedly held against rotation, a fourth ring gear fixedly coupled to the third shaft, a fourth planet carrier, and at least one planet gear supported for rotation on the fourth planet carrier and in continuous meshing engagement with the fourth sun gear and the fourth ring gear; and 
 a third clutch configured to selectively couple the fourth planet carrier to the output. 
 
     
     
       7. The transmission of  claim 6  wherein the fourth simple planetary gear set is positioned radially outside the first and second gearing arrangements. 
     
     
       8. The transmission of  claim 6  wherein the fourth simple planetary gear set is positioned radially outside the third gearing arrangement. 
     
     
       9. The transmission of  claim 1  wherein the fifth gearing arrangement comprises a fourth clutch configured to selectively couple the fifth shaft to the output. 
     
     
       10. The transmission of  claim 1  wherein the input rotates about an input axis and the output rotates about an output axis parallel to and displaced from the input axis. 
     
     
       11. The transmission of  claim 10  wherein the fourth gearing arrangement comprises:
 a first axis transfer gear supported for rotation about the input axis; 
 a second axis transfer gear fixedly coupled to the output and in continuous meshing engagement with the first axis transfer gear; and 
 a third clutch configured to selectively couple the first axis transfer gear to the third shaft. 
 
     
     
       12. The transmission of  claim 10  wherein the fifth gearing arrangement comprises:
 a third axis transfer gear fixedly coupled to the fifth shaft; 
 a fourth axis transfer gear supported for rotation about the output axis and in continuous meshing engagement with the third axis transfer gear; and 
 a fourth clutch configured to selectively couple the fourth axis transfer gear to the output. 
 
     
     
       13. A transmission comprising:
 an input configured to rotate about an input axis; 
 an output configured to rotate about an output axis offset from the input axis; 
 a first simple planetary gear set having a first sun gear, a first ring gear, a first planet carrier coupled to the input, and at least one planet gear supported for rotation on the first planet carrier and in continuous meshing engagement with the first sun gear and the first ring gear; 
 a first axis transfer gear coupled to the first sun gear; 
 a second axis transfer gear coupled to the output and in continuous meshing engagement with the first axis transfer gear; 
 a third axis transfer gear fixedly coupled to the first ring gear; 
 a fourth axis transfer gear coupled to the output and in continuous meshing engagement with the third axis transfer gear; and 
 a first gearing arrangement configured to selectively impose a plurality of fixed speed ratios between the input and the first sun gear. 
 
     
     
       14. The transmission of  claim 13  wherein:
 the first planet carrier is fixedly coupled to the input; 
 the first axis transfer gear is selectively coupled to the first sun gear by a first clutch; 
 the second axis transfer gear is fixedly coupled to the output; and 
 the fourth axis transfer gear is selectively coupled to the output by a second clutch. 
 
     
     
       15. The transmission of  claim 14  wherein the first gearing arrangement comprises:
 a second simple planetary gear set having a second sun gear, a second ring gear fixedly coupled to the first sun gear, a second planet carrier, and at least one planet gear supported for rotation on the second planet carrier and in continuous meshing engagement with the second sun gear and the second ring gear; 
 a third simple planetary gear set having a third sun gear, a third ring gear fixedly coupled to the second planet carrier, a third planet carrier fixedly coupled to the first sun gear, and at least one planet gear supported for rotation on the third planet carrier and in continuous meshing engagement with the third sun gear and the third ring gear; 
 a third clutch configured to selectively couple the third sun gear to the input; 
 a fourth clutch configured to selectively couple the second sun gear to the input; 
 a first brake configured to selectively hold the second sun gear against rotation; and 
 a second brake configured to selectively hold the second planet carrier against rotation. 
 
     
     
       16. The transmission of  claim 15  further comprising a one-way-brake configured to constrain the second planet carrier to rotate in only one direction. 
     
     
       17. The transmission of  claim 15  wherein the first simple planetary gear set is positioned radially outside the second and third simple planetary gear sets. 
     
     
       18. A transmission comprising:
 a simple planetary gear set having a sun, a ring, and a carrier fixedly coupled to an input; 
 first and second axis transfer gears coupled to the sun and ring respectively; 
 third and fourth axis transfer gears coupled to an output and meshing with the first and second gears respectively; and 
 a gearing arrangement configured to selectively impose a plurality of fixed speed ratios between the input and the sun. 
 
     
     
       19. The transmission of  claim 18  wherein the first axis transfer gear is selectively coupled to the sun and the third axis transfer gear is fixedly coupled to the output. 
     
     
       20. The transmission of  claim 18  wherein the second axis transfer gear is fixedly coupled to the ring and the fourth axis transfer gear is selectively coupled to the output.